Standing stark-naked for three minutes before a roomful of strangers is not nearly as challenging as eating live cockroaches.

That’s the lesson to be learned from tonight’s episode of “Fear Factor” (8 p.m. on WNBC/Ch. 4).

No one keeps track of these things, but it seems safe to say that forcing contestants to go naked on TV is a first for an American game show.

The six contestants you’ll see tonight had no problem shedding their clothes for the episode’s first dare – although the men turned out to be more self-conscious about their physical attributes than the women.

“Well, the first thing that went through my mind is the size of my package – I think it’s a little bit small!” said one of them – burly Mike Amoroso, a tattooed construction worker from Smithtown, L.I. – after he strutted his stuff.

Apparently, Amoroso was less impressive than he would have liked. Commented host Joe Rogan as he observed Amoroso on the runway: “It’s a grower, not a show-er!”

Later, Amoroso blamed his shortcomings on male “shrinkage,” a phenomenon that was last explored on NBC in a memorable episode of “Seinfeld” (in fact, that episode aired last Thursday night on Ch. 5).

“You know, it’s nervous up there and everything just shriveled up!” Amoroso explained, sounding a bit like George Costanza.

All the nudity on tonight’s “Fear Factor” is full-frontal but well-pixellated – even when some of the contestants turn cartwheels in the altogether.

Elsewhere on the show, the contestants chow down on live – and crunchy – hissing cockroaches from Madagascar.

And later, they’re each lowered into freezing-cold water chained to a heavy weight from which they can escape only if they can locate an underwater key before drowning.